Neither company is talking publicly, and the Chronicle's source is choosing to remain anonymous, but it appears that Tesla and Apple may have been at least a little bit interested in working together well ahead of Ahmad's call. He wrote that buying Tesla would bring another Steve Jobs-like figure (Musk) to the computer giant as well as give the maker of iPhones and iPads another market to explore (remember the iCar idea?). The Chronicle does admit that there's no upside for Tesla that's quite as obvious, and one analyst said a partnership would make more sense than a buy out.
There could be other scenarios on the table, as well. Perhaps it was to discuss a joint giga-battery plant? Or maybe Musk's visit to Cupertino was just a courtesy call, in case Tesla ever needs access to Apple's famously deep pockets. We don't know, but the news does give us a slew of interesting possibilities to ponder. There's a lot more over in the Chronicle, including how Apple may be branching out into new medical devices.